Spring of nickel-iron alloy



Fatented Sept. 25, 19.34

SPRING F. NICKEL-IRN ALLQY Reinhard Straumann, Waldenburg, Switzerland No Drawing.

Application February 19, 1932,

Serial No. 594,149. In Germany April 18, 193i Claims.

The lmown nickel-iron alloys, as are used for example in the manufacture of spiral springs for watches, with positive thermo-elastic coefilcient, have the great disadvantage of too low hardness. The springs heavily damp the vibrating system, which among other disadvantages leads in particular to large energy losses. Further, such springs easily deform which makes their use in small watches difficult and renders their use in marine chronometers impossible owing to the permanent deformations of the end curves produced as a result of the low hardness. These known springs are brought to glowing heat in the fixation of their shape talnng place at high temperature (600 to 700 C.) and thus lose the hardness produced in rolling.

It has already been proposed to harden nickeliron alloys for watch springs by an addition of beryllium. An increase in hardness can, it is true, thus be obtained, but the thermo-elastic coefiicient of the alloy is to a certain extent unfavourably affected.

The present invention relates to a spring of nickel-iron alloy with a hardening addition of beryllium, in particular for thermo-compensated vibrating systems, in which the increase of hardness of the spring takes place during the fixation of the shape thereof and in which the thermoelastic requirements are completely satisfied. According to the invention, with a content of to nickel and 0.1 to 3% beryllium, a quantity of other alloying substances such as tungsten, molybdenum, chromium and so forth in amounts up to 30% is added to the main alloying ingredients in such relative proportion that not only does an increase in hardness of the spring take place during the fixation of shape thereof at high temperature, but also the thermo-elastic coefficient of the alloy is brought to the required value for compensating spiral watch, springs. The value and rate of change of the thermoelastic coefficient is strongly influenced on one hand by the amount of the nickel content and on the other hand by the amount of beryllium as well as of tungsten, molybdenum and so forth, so that according to the proportions of the alloying ingredients, the coefiicient can be made zero, negative or positive as desired. The addition of beryllium, which can amount to 0.1 to 3%, in combination with the addition of tungsten, molybdenum and the like which used alone or several together can amount to 530% of the alloy, thus makes it possible by suitable choice of their relative proportions to obtain any desired value of the thermo-elastic coeflicient and its linear variation between and +50 C. together with the achievement of the novel effect of hardening during the fixation of shape of the spring. 7

Some examples of the alloy according to the invention are the following:

1. 30% nickel, 0.1 to 0.5% beryllium, 8% tungsten, remainder iron, constituting an alloy with positive thermo-elastic coefficient.

2. 27% nickel, 8% tungsten, 1% beryllium, remainder iron, constituting an alloy with negative thermo-elastic coefiicient.

3. 30% nickel, 0.5% beryllium, 6% molybdenum, remainder iron.

4. 30% nickel, 4% tungsten, 3% molybdenum, 1% beryllium, remainder iron.

What I" claim is:-

1. As a new article of manufacture, a watch spring consisting of a nickel-iron alloy of great hardness with controlled and predetermined thermo-elastic coeihcient, comprising 25 to 40% nickel, 0.1 to 3% beryllium, 5-30% of a metal from the group comprised of tungsten, molybdenum and chromium, and the balance substantially iron, the nickel contents being balanced against the content of beryllium and refractory metals to fix the said coefiicient at the desired value and sign while the hardness is maintained substantially constant.

2. As a new article of manufacture, a watch spring consisting of a nicl el-iron alloy of great hardness with. controlled and predetermined thermo-elastic coeihcient, comprising 26-32% nickel, 0.3 to 1.2% beryllium, 5-12% of a metal from the group comprised of tungsten and molybdenum, and the remainder substantially of iron.

3. As a new article of manufacture, a watch spring consisting of a nickel-iron alloy characterized by great hardness and by a positive thermoelastic coefficient, comprising 30% nickel, 0.l to 0.5% beryllium, 8% tungsten, and the remainder substantially of iron.

4. As a new article of manufacture, a watch spring consisting of a nickel-iron alloy characterized by great hardness and by a negative thermoelastic coeiiicient, comprising 27% nickel, 1% beryllium, 8% tungsten, and the remainder substantially of iron.

5. As a new article of manufacture, a watch spring consisting of a nickel-iron alloy characterized by great hardness and by a negative thermoelastic coefficient, comprising 30% nickel, 1% beryllium, 3% molybdenum, 4% tungsten, and the remainder substantially of iron.

REINHARD STRAUMANN. 

